In 1974 Hans Burgschmidt was sixteen years old, living in the Canadian Prairies, working in a photography studio darkroom, elbow-deep in chemicals all day long. “Is this what life is about?” he asked a high school friend. “You need to meditate,” was the reply. Not long after, Hans attended a lecture at the local library, where a man in a suit spoke about the scientific benefits of relaxation. He pressed Play on the industrial-sized U-Matic video player and there was Maharishi Mahesh, the Indian yogi who initiated the Beatles into the mysteries of Transcendental Meditation (TM) and launched the meditation careers of thousands of Western devotees.

“An infinite ocean of peace and love and happiness awaits you,” said the radiant Maharishi, with his flowing hair and his garland of flowers. “What’s not to like?” Hans thought, and got in touch with a local TM chapter.

Soon after he began his meditation practice, exactly as advertised, he found himself transported from his parent’s basement into a shimmering inner space of light and colour and bliss. “Eventually you get so expanded and the mantra becomes so refined that you are taken to the silent source of thought – it was wonderful.”

Hans was hooked. Next, he enrolled himself in advanced courses and in the late 70s he left for Maharishi International University in Fairfield, Iowa, hoping to become a teacher.

But somewhere along the line Hans became disenchanted. Maybe it was the dubious “levitation” training, or the dogmatism of his fellow teachers, or the “almost abusive” way the school administrator overworked their staff. “The discrepancies between what was promised and what was really happening kept growing,” Hans told me. “Eventually I had to move on.”

Thus began Hans’ long career as an itinerant spiritual seeker. He hit all the New Age mainstays: Osho and then Da Free John in the 80′s, trance channeling and primal scream therapy and past life regression in the 90′s. But the same pattern of finding the limits of the guru or the practices kept repeating itself. Finally in 2006 he met a teacher he could trust – one of my own teachers, in fact – the Buddhist scholar and future neuroscience-consultant Shinzen Young. “No BS, real down to earth, just an ordinary guy teaching a well-crafted version of techniques that have been tested by Buddhists for thousands of years.” The technique was vipassana, one important – and increasingly popular – aspect of which is known as “mindfulness.”

“I found it invigorating,” says Hans. “It was much more active than other techniques I had learned, I could feel the power of it.”

Everything was fine,until three weeks after his first retreat, when, in Hans’ words, “something changed.” My sense,” says Hans, “is the technique precipitated something that was already there. I mean I had done a lot of meditating in other traditions by then. They softened me up. Whatever the case, I don’t think it could have turned out any other way.”

Hans was at home making his bed, when the room suddenly appeared “very far away.” But the room hadn’t changed; he had. The part of Hans that had once looked out at the world, the core we take for granted as the “self”,had without any warning disappeared.

“All of my thoughts, all my processing – none of it referred to me. They weren’t happening to anybody. It was all just an unfiltered barrage of sensations happening in space. It was the most terrifying and alienating thing that ever happened to me.” And Hans has been living with various degrees of this experience for the past seven years.

To understand what happened to Hans, you need to understand something about how meditation works in general, and vipassana in particular. Most meditation techniques are designed to shift a person’s orientation from a limited personal identity to the broader ground of their experience. Vipassana does this by deliberately and systematically untangling the different strands that make up oursense of self and world; in the Pali language (the ancient Indian scriptural dialect of Buddhism) theword “vipassana” means “seeing into” or “seeing through.”

Practicing vipassana, you have more space to make appropriate responses, and more space, too, around your looping thought-track, which can dramatically reduce stress and anxiety as well as raise a person’s baseline levels of happiness and fulfillment. This is one reason why mindfulness has become the technique of choice for thousands of clinicians and psychotherapists, and there is now a considerable body of scientific research demonstrating these and other benefits.

Yet most of the clinicians who so enthusiastically endorse mindfulness do not have a proper understanding of where it can lead. The fact is that mindfulness in large doses can penetrate more than just your thoughts and sensations; it can see right through to the very pith of who you are – or rather, of who you are not. Because, as Buddhist teachers and teachers from many other contemplative traditions have long argued, on close investigation there doesn’t appear to be any deeper “you” in there running the show. “You” are just a flimsy identification process, built on the fly by your grasping mind—a common revelation in meditation that happens to be compatible with the views of many contemporary neuroscientists.

In fact, the classic result of a successful vipassana practice is to permanently recognize the impermanence (anicca), the selflessness (anatta), and the dualistic tension or suffering (dukkha) of all experience, which may sound like an Ibsen play, but this is the clear empirical understanding that many otherwise sensible practitioners report. For most people this shift is the most profoundly positive experience of their lives. In the words of Shinzen Young, “it allows a person to live ten times the size they would have lived otherwise, it frees them from most worries and concerns, it gives them a quality of absolute freedom and repose.”

But once in a while, something goes wrong. In Buddhism this is known as falling into “the pit of the void.” Young is more modern: “Psychiatrists call it Depersonalization and De-realization Disorder, or DP/DR. I call it ‘Enlightenment’s evil twin’.”

For Hans, what began as confusion and disorientation led within a few hours to extreme panic. The emptiness was ominous – in his words, a “deficient void.” One moment the world seemed far away, the next it wastoopresent, a “barrage” of overwhelming sensations. “It was like I had no protective filter or skin – sounds and sights became incredibly abrasive. Hearing the phone ring was like someone running a thousand volts of electricity through me. I also had feelings of being stretched and twisted inside out, like I was morphing into some kind of animal. I had no idea what was happening – I thought maybe I was getting premature Alzheimer’s.”

Over the next few months Hans spent hours with Young on the phone, but despite the counseling, none of his symptoms went away – if anything, he says, the selflessness, the rawness of sensations and the associated fears became even more disconcerting. One by one, all the meaningful parts of Hans’ life dropped away: his love of photography, of art, even his sex drive.

“I lost my will to do anything – none if it had any meaning. You could say that I no longer understood existence. I would wake up in the morning and go ‘OK, this is my body, this is me, and I guess I’m doing this but I no longer understood it. I no longer understood agency, what makes other bodies move, what animates life. Sometimes there was a wondrous quality to this bafflement – I felt the awe and the mystery – but most of the time it was aimless and tormenting.”

Was Hans experiencing a slow-motion nervous breakdown unrelated to his meditation practice? Or was the experience of depersonalization triggered by meditation?

He was able, just barely, to keep working, although he says he has no idea how he was able to do this since, in his words, “I often couldn’t understand what people were saying – all I would hear is the weird texture of their speech patterns, there was no meaning to any of it.” His own responses, too, came as a surprise. “At times I would hear myself speaking and I had no idea where the words were coming from or what they meant. I felt like an imposter.”

Hans is not alone. If the very real benefits of mindfulness add up to the good-news mental health story of our time, then, like so many good things, there is also a shadowy seam, an experience known popularly as theDark Night, after the writings of the famous Carmelite mysticSt. John of the Cross.

More meditators and practitioners are beginning to speak openly about the challenges associated with practice. The importance of this cannot be overstated, for there are those in the scientific community who believe that taking these reports seriously may one day provide key insights into both mental illness, and the mystery of contemplative transformation. They may in fact bevery different expressions of a single underlying dynamic.

Some researchers are already studying this.Willoughby Brittonis a meditator and a clinical psychologist at Brown University. After encountering some of this difficult territory herself, she began an ambitious research project to document the full range of phenomena that can happen as a result of practice. The initiative is called “The Varieties of Contemplative Experience” (Britton’s group have just published their first paper,here).

Over the past three years, Britton and her colleagues have conducted detailed interviews with over forty senior Buddhist (and some non-Buddhist) teachers and another forty or so practitioners about challenges they’ve either experienced themselves, or, in the case of teachers, seen in their students. The study’s current research design cannot answer the question of what percentage of practitioners run into problems, although Britton did tell me that serious complications that require inpatient psychiatric hospitalization probably affect less than one percent of meditators. “Milder, more chronic symptoms,” she says, “will be higher – but no one knows how high.”

The full range of symptoms, from mild to intense, include headaches, panic, mania, confusion, hallucinations, body pain and pressure, involuntary movements, the de-repression of emotionally-charged psychological material, extreme fear and – perhaps the central feature – the dissolution of the sense of self.

But, as she reports in a recentinterview,the most surprising finding for Britton has been the duration of impairment, which she defines as the inability of an adult to work or take care of children. “We’ve been deliberately looking for worst-case scenarios, so I expect this number will go down as we get more data, but right now we are finding that people in these experiences are affected for an average of three years, with a range of six months to twelve years.”

Britton has found that two demographics seem to be affected more than other: young men aged eighteen to thirty, who, in the way of young men, go for months-long retreats in Asia and pursue hardcore practice and log ten to twenty hours of meditation a day. “We had to create a “Zealotry Scale” says Britton, dryly, “it was such a major predictor.” The other large group, she says, is middle-aged women. “These ladies have been going to, say,Spirit Rock Meditation Centrefor last ten to twenty years, have a nice hour-a-day practice, and then seven or ten years into it something happens.”

The situation is complicated by the fact that a period of difficulty is actually a perfectly normal part of many meditation practices. A well-meaning therapist might label this pathological, when what might be more helpful to the “patient” is guidance from an experienced meditation teacher. Within vipassana traditions, someclassic textstalk about the “dukkha ñanas” – challenging stages that are actually a sign of progress. These are a natural response to the layer of mind being exposed; with a teacher’s help, the student can move through their Dark Night in a matter of days or hours. Indeed,some teachers argue that the skills practitioners acquire in coping with these passagesare often the very ones that allow them to progress to more liberating stages of the path.

Shinzen Young writes, “It is certainly the case that almost everyone who gets anywhere with meditation will pass through periods of negative emotion, confusion, disorientation, and heightened sensitivity to internal and external arisings. The same thing can happen in psychotherapy and other growth modalities. For the great majority of people, the nature, intensity, and duration of these kinds of challenges is quite manageable.”

According to Young, thereal Dark Night occurs when, as in Hans’ case, a practitioner has difficulty integrating insight into selflessness. This is something he says he has only ever seen a few times in his four decades of teaching.

Perhaps surprisingly, Britton’s research has so far not revealed any clear associations between meditation-related difficulties and prior psychiatric or trauma history. Problems can occur in individuals with no identifiable red flags; conversely, individuals with multiple red flags (bipolar disorder, trauma history, and so on) can do intensive retreats without any difficulties whatsoever.

“We have to be careful,” Britton told me, “about jumping to conclusions and excluding people prematurely from meditation’s possible benefits. My personal opinion is that the place where we need most help is not in identifying at-risk people so much as improving support systems.”

Britton gets two to three emails a week from people looking for help, so this is something she thinks a lot about. “Just talking about the experience with someone and hearing that none of it is new … this has a hugely positive effect on people. That’s eighty percent of what needs to happen. Just normalizing the experience.” To that end, she has already founded both a space and a website to provide resources for practitioners in need, and also to educate teachers and clinician about the full range of meditation’ effects.

“Length of impairment is directly related to how much access the student has to a good teacher. Many of the people I’ve spoken to have been through dozens of therapists and meditation instructors and most have no idea what to do.”

Young has his own techniques for helping meditators work with Dark Night phenomena. (Here, you can read about them in detail.) Hans adds one more: serious fitness. “Pilates, weight-training, yoga – I now do it all. For me, I finally figured out that I needed to integrate these changes into my physical body. Ultimately this is what turned the corner for me.”

Seven years after his drop into the pit of the void, Hans is arriving at a better place. Not a normal place, mind you – and here his laugh is a bit hysterical: “What’s normal? I still live in emptiness and wake up every morning with no idea who I am.” But he no longer gets panic attacks, or feels ten thousand volts of electricity irradiate his senses every time the phone rings. His sex drive has returned, and with it a new longing for a relationship. He also has a strong interest in helping others manage similar problems.

“So much of it is about patience,” he says. Over the past seven years, the words of one teacher kept circling around in his head: “If life gives you nothing you want and is not on your own terms, would you still have the generosity to show up for it?” There’s no easy “yes” to that question.